Electrochemical cells are energy conversion devices that are usually classified as either electrolysis cells or fuel cells. Proton exchange membrane electrolysis cells function as hydrogen generators by electrolytically decomposing water to produce hydrogen and oxygen gases. The hydrogen gas is then removed and used as a fuel. Referring to FIG. 1, a section of an anode feed electrolysis cell of the related art is shown generally at 10 and is hereinafter referred to as xe2x80x9ccell 10.xe2x80x9d Reactant water 12 is fed into cell 10 at an oxygen electrode (anode) 14 to form oxygen gas 16, electrons, and hydrogen ions (protons). The chemical reaction is facilitated by the positive terminal of a power source 18 connected to anode 14 and a negative terminal of power source 18 connected to a hydrogen electrode (cathode) 20. Oxygen gas 16 and a first portion 22 of the water are discharged from cell 10, while the protons and a second portion 24 of the water migrate across a proton exchange membrane 26 to cathode 20. At cathode 20, hydrogen gas 28 is formed and is removed for use as a fuel. Second portion 24 of water, which is entrained with hydrogen gas, is also removed from cathode 20. The removal of hydrogen is generally effectuated through a gas delivery line.
Cell 10 includes a number of individual cells (not shown) arranged in a stack with reactant water 12 being directed through the cells via input and output conduits formed within the stack structure. The cells within the stack are sequentially arranged, and each one includes a membrane electrode assembly defined by a proton exchange membrane disposed between a cathode portion and an anode portion. The cathode portion, anode portion, or both may be gas diffusion electrodes that facilitate gas diffusion to the proton exchange membrane. Each membrane electrode assembly is supported on both sides by screen packs within flow fields. The screen packs facilitate fluid movement and membrane hydration and provide mechanical support for the membrane electrode assembly.
Power to the electrolysis cell is interrupted when, after sensing a condition such as a pressure variation in the gas delivery line, a control unit signals an electrical source that drives a reference voltage applied across a potentiometer to an extreme value. In such a system, the control unit is directly dependent upon the detection of a mass leak from the gas delivery line. Depending upon the preselected conditions of the system, when the power interruption capability is dependent upon the detection of a mass leak, a delay between the time that the leak occurs and the time at which the system is shut down may be experienced. Such systems do not provide early detection of potential problems but instead simply react to signals indicative of problems currently existing in the operation of the cell.
A fan flow sensor for a hydrogen generating proton exchange member electrolysis cell is disclosed herein. The fan flow sensor includes a switching device and a sail slideably disposed on the switching device. The sail is configured to actuate the switching device in response to an airflow from a fan.